Spray nozzles, especially those used with spray painting systems, atomize the liquid paint by means of atomizing air which enters the nozzle via a chamber which surrounds a fluid nozzle. The atomizing air is then impinged on the end of the chamber and exits via a central aperture located at the end of the chamber. The paint is atomized by the violent forward motion of this air as it exits the nozzle via the aperture. The initial conventional pattern of the atomized liquid and air mixture is a circle because the exit aperture is circular.
The term pattern is defined as and used herein to describe a cross section of the atomized liquid cloud in a plane perpendicular to the direction of the spray of the fluid nozzle. When the compressed air source for a spray painting apparatus utilizes a high volume, low pressure compressor, it is conventional for the nozzle on the spray painting gun to have a central aperture which is considerably larger than the fluid nozzle. Therefore, the large amount of air utilized in a conventional nozzle is due to the relative size of the central aperture to that of the fluid nozzle. This excess air, air beyond that required to atomize the liquid properly, constitutes an energy waste as well as a pollution problem. The air is a pollution problem since the air in a paint system will tend to carry the paint solvent and the more air that is used the more dilute the solvent and the more air that must be processed for the removal of solvents utilizing extremely difficult low concentration removal techniques.
Therefore, there is a need for an improved spray nozzle which utilizes less air, and more efficiently utilizes the air that it actually uses.
The pattern of a spray nozzle is conventionally adjusted by impinging additional air jets into the original circular pattern at a location beyond the outlet aperture. Standardly two oppositely directed jets produce a flat or oval pattern, and if those jets are very powerful it produces a flat fan type spray pattern which is many times wider than it is high. However, in production line spraying, there are needs for other than such a flat or oval pattern, especially when spray painting the reverse sides of objects or spray painting in an out-of-position way and also the traditional problem of painting the insides of angular surfaces.
Therefore, there is also a need for improved pattern control in spray nozzle systems and the ability to adjust the pattern to other than a flat or oval pattern. It would additionally be desirable if such adjustments or modifications of the pattern could be achieved without the necessity of changing the nozzle in use.